A method of operating a mobile telecommunications device including cellular communication means operable to communicate with a cellular telecommunications network base station and white space communication means operable to communicate with a non-cellular white space access point, the method including determining the availability of white space and selectively enabling white space communication in dependence upon the determination. Controlling transmission of user data in the white space may be by exchanging control data with the cellular telecommunications network base station such that the control data controls the transmission of user data in the white space. White space communication need not be implemented in uplink and may be used in the downlink alone.